Picture framing is a rapidly growing industry which has been aided and abetted by the development of extruded metallic or plastic frame members which can be cut to any desired length and connected together at the corners by suitable corner connectors. A common feature of such frame members is a generally C-shaped channel extending the length of the frame member with a pair of reentrant flanges separated by a gap. The corner connector is usually positioned within the channels of meeting frame members with access to appropriate fastening or tightening means being provided through the aforementioned gap.
The metallic and plastic frame members presently in use usually have sharp edges or corners which can mar the surface of a wall when a picture is being hung or when it is moved, perhaps during dusting or cleaning. Furthermore, when a picture hangs directly against or close to a wall there is little or no air circulation behind the picture. Research has shown that air circulation is essential in prolonging the life of paintings, pictures, prints, documents, photographs, etcetera and thus it is important to space a picture or painting away from a wall surface.
With solid frames of plastic or wood a spacer or standoff can be used to move the frame out from the wall, the spacer being in the shape of a button, dimple or foot, approximately 3 mm in height, with an adhesive back for attachment to the frame. These spacers do have definite shortcomings in that the adhesive prematurely dissolves, causing the spacer to fall off leaving the frame contaminated with a tacky dirt-collecting film which, if unnoticed, could soil the wall. In addition, the height of about 3 mm is much less than the recommended height of 10-15 mm. Such spacers are even less effective with extruded metallic or plastic frames because of the gap between the flanges at the rear and the fact that the flanges usually do not provide enough surface for proper adhesion of a spacer of the aforementioned variety.